The invention relates to a printing mechanism, particularly for labelling devices, with an adjustable printing attachment, an inking rocker arm which can be swung out and is swung out of its movement path on moving the printing attachment and a transfer roller which inks the set type of the printing attachment and cooperates with a supply roller arranged on a roller holder freely rotatable about a spindle parallel to the transfer roller spindle.
Such a printing mechanism is known from Federal Republic of Germany Auslegeschrift (DE-AS) No. 26 39 927 and has a return spring holding the inking rocker arm in the inking position and a roller holder mounted on the inking rocker arm. This known printing mechanism has the disadvantage that during the printing process the roller holder projects forward beyond the leading edge of the apparatus. When printing labels it is desirable that no part of the printing mechanism projects beyond the leading edge of the casing, so that the labelling device can also be used close to walls.
In addition, an inking mechanism with a transfer roller and an inking roller for a hand stamp is known from British Pat. No. 322 263. In this known inking mechanism the transfer roller is placed on a roller holder mounted on the inking rocker arm and is pivotable about a spindle parallel to the rocker arm spindle and is pressurised by a pressure spring bearing against the rocker arm.
In the known hand stamp the inking rocker arm is pivotably mounted on the printing attachment and its swivel pin performs the printing attachment travel and for this purpose is guided in a longitudinal guide. Furthermore the inking rocker arm is connected by means of a cam to the hand stamp frame, so that the movement of the rocker arm is forcibly mechanically coupled with the movement of the printing attachment.
The rollers, i.e. the transfer roller and the inking roller are also mechanically coupled. On raising the printing attachment these rollers are further rotated by means of a driving arm.
Due to this mechanical coupling mechanism the known hand stamp is costly and fault-prone, as well as being disadvantageous from the assembly and maintenance standpoints. In addition, the replacement of the inking roller is a time-consuming task and an accurate position between inking roller and transfer roller is not ensured, so that the type is not always uniformly inked independently of ambient conditions.